1. Field of the Invention
The present invention relates generally to wireless networking, and, in some preferred embodiments to the prevention of lost packets due to network layer and link layer transition.
2. General Background Discussion
A mobile network seeks to provide security, smooth handoff, minimal data loss and minimal delay. Many of the existing networks involve communication between a Mobile Node (MN) and a Buffering Node (BN). Buffering Service in these cases is inefficient as it requires the MN to explicitly solicit the service. As a result, the amount of wireless signaling traffic is great, and the MN's energy usage is also great, reducing the amount of energy available for sending and receiving messages until a consensus is reached.
Some of the drawbacks of the existing networks are detailed below.
One drawback pertains to an extension to the lUv6 Router, which calls for a router to advertise its ability to support buffering, and which requires the MN to beg the Buffering Node for its desired buffer size, requiring a high volume of messages. This high volume of messages pertaining to BN discovery, as well as probes and responses concerning the service and service negotiation not only consumes scarce network resources, but also adds additional latency to the network.
Another drawback pertains to buffer size. Once a MN receives an advertised indication that Buffering Services are available, the MN may request a specific buffer size. Depending on available resources, the BN may or may not accept this request. Likely, the BN is constrained by a buffer protocol, in which case, if the MN request exceeds the upper limit, the BN may offer a smaller buffer size. Further, if the BN is critically low in available resources, it will send messages back and forth to the MN in an attempt to find an agreeable buffer size, attempting to arrive at a compromise position. In spite of this negotiation, the end result of the requests may be a denial of service. This process leads one to conclude that the BN is in control, and that the MN has no option to protect the packets of data it is trying to send to the BN. As the MN has no other alternative in the event the BN denies service, the MN does not establish communications with the BN or waste its time and energy.
Another drawback occurs when the router cannot accept new requests for buffering, due to resource shortages, but still continues to advertise its capability of buffering and then replying negatively to initialization requests. The router does not have the ability to stop advertising when it is unable to provide buffering because this will adversely affect the handoff operation. This situation creates an unnecessary burden on the network and is illogical as well—advertising services while being unable to provide them.
Another drawback is concerned with the network awareness of the movement of the MN with regard to buffering control protocols in Network Controlled Mobile Assisted (NCMA) handoff mode. In this situation, the previous router supplies the new router with current state information for the MN before the handoff actually occurs and also directs the buffered packets to the new router without the MN's intervention. The MN is thus not required to negotiate with the network and explicitly request initialization of the buffering state and subsequent buffered packet forwarding. However, in many cases, the MN still has to negotiate because the protocols require the MN to do so. Therefore, even in a NCMA case, the MN will always have to issue a Smooth Handoff Initialization (SHIN) to the new router, because it has received a router advertisement for service.
Yet another drawback is directed towards the Buffering Control Protocols requiring the MN to send an anticipated buffer size and time duration for buffer usage. Since Internet Protocol (IP) traffic is of a bursty nature; that is, a continuous transfer of data without interruption from one device to another, any MN estimation may not be accurate, which results in either over-or underestimating the pre-buffering size. Even if an accurate estimation is made by the MN, the buffer size demanded by the MN may not be immediately available, but may become available only moments later, when the BN has completed servicing other MN(s). This instantaneous decision (to accept, deny, or compromise) is based solely on the conditions present at that instant, without regard to conditions in the near future.
Still another drawback is the occurrence of a “time-limited timeout” condition that affects the efficient performance of both the MN as well as the BN since the BN automatically stops buffering without receiving any message (i.e., BReq[stop]) from the MN. In fact, the BReq[stop] message serves a double purpose. First, it stops the buffering event; and second, it informs the BN of the new CoA (Care of Address). In the event of a time-limited timeout, the BN stops buffering without receiving a BReq[stop] message and without receiving the flushing destination (CoA). In order to overcome this situation, the MN must send a separate message “BReq[ext]” to inform the BN, the new CoA, and request an extension of buffering time. If this situation occurs repeatedly, the BN will have received multiple CoAs (though it will use the last CoA for flushing the data packets). This entire situation is undesirable due to the required increased signaling burden and wasted memory required to hold the redundant information of several CoAs. Also, since there is a requirement on the MN to send BReq[ext] messages before the end of the time-limited timeout period, the MN battery life is adversely affected.
In view of the foregoing, an improved buffering service is needed in the wireless network art, which includes a complete architecture harnessed to provide a comprehensive buffering service that offers packet loss prevention to packets in transit during handoffs. More particularly, the improved buffering service of the present invention provides a well-managed buffering architecture harnessed to provide maximum buffer size that best meets the needs of MNs without solicitations or negotiations; reserves buffer size based on multiple factors, including MN's current application, network speed in which MN is roaming, and near future demand and resource predictions; is completely autonomous so that the BNs perform their tasks by communicating amongst other peer BNs and network entities without involving assistance from the MN; can be implemented without introducing new protocols that would enable MNs to communicate with the network for this specific service.